The present invention relates to toilets provided with improved trapways.
Conventional toilets have a bowl portion and a storage tank portion, usually formed in one or two main pieces. A serpentine passage is typically positioned behind and below the bowl to transport the contents of the bowl to waste/sewer/septic plumbing lines of the building. This passage is generally referred to as the “siphon” or “trapway”.
An up leg portion of such a passage is normally filled with water to “trap” sewer gases downstream thereof, so as to prevent them entering the building interior. Water is maintained in the bowl and the up leg part of the trapway by an arched portion of the trapway. The trapway (sometimes in conjunction with an adjacent jet) generates a siphon to evacuate the bowl contents when a normally air/vapor-filled downstream portion of the trapway is rapidly filled with water during the flush cycle.
The trapway thus helps retain water in the bowl prior to flushing, and then assists in the formation of a siphon helpful in removing waste during the flush cycle. Achieving these dual functions can be relatively easy where a large volume of water is used during a single flush cycle. However, for environmental and water conservation reasons many jurisdictions now restrict the sales of toilets which use too much water per flush. For example, some such regulations require no more than 1.6 gallons (6.06 liters) of water to be used per flush cycle.
Achieving an effective flush with that little water when the bowl is filled with feces, toilet paper, and other solids can be difficult. Hence, it is common with respect to some such low water usage toilets for consumers to flush the toilet twice or more to clean the bowl to their satisfaction when other than just urine is present. This not only frustrates the regulatory and conservation goals, it is time consuming for consumers.
Even where a toilet is reasonably efficient in its cleaning when using low amounts of water, there is also an interest in minimizing the time that the flush cycle takes. A short flush cycle has a number of advantages. For example, the period during which the toilet is generating maximum noise may be reduced if the flush cycle takes less time. This may be of interest if the toilet is being used during the middle of the night and the user wishes to minimize the possibility of others who are sleeping (e.g. a baby) being disturbed. Another advantage of a short flush cycle is that with such a cycle, if a second flush is needed to complete bowl cleaning, it can begin sooner.
Various attempts to accomplish a shorter flush cycle have included specially shaping the flow path, controlling the state of flow (turbulent or laminar), and/or reducing or eliminating the occurrence of air pockets at particular locations in the trapway. For example, U.S. Pat. No. 5,918,325 discloses a trapway modified in various ways to attempt to render flushing more optimal. See also U.S. Pat. Nos. 3,484,873, 5,706,529 and 6,292,956. The disclosures of these patents, and of all other patents and publications referred to herein are incorporated by reference as if fully set forth herein.
However, attempts to develop quick flush action having efficient cleaning with low volumes of water can be frustrated by “blow back”, which is a tendency of such trapways to develop reverse flow of air from the plumbing lines into a low pressure region of the trapway. Accordingly, there is still a need for low volume flush toilets that have a short flush cycle, yet clean even solid bowl waste effectively and efficiently.